Meropenem Dosing and Clinical Use
Standard Dosing in Normal Renal Function
For most serious bacterial infections in adults with normal renal function, administer meropenem 1 gram IV every 8 hours, or 500 mg every 8 hours for uncomplicated skin infections. 1
Adult Dosing by Indication
- Complicated skin and skin structure infections (cSSSI): 500 mg IV every 8 hours 1
- Complicated intra-abdominal infections: 1 gram IV every 8 hours 1
- Infections caused by P. aeruginosa: 1 gram IV every 8 hours (higher dose required) 1
- Carbapenem-resistant Enterobacteriaceae (CRE): 1 gram IV every 8 hours by extended infusion (3 hours) as part of combination therapy 2, 3
- Carbapenem-resistant Acinetobacter baumannii (CRAB): 2 grams IV every 8 hours 4, 2
Administration Method
- Standard infusion: 15-30 minutes for all doses 1
- Bolus injection: 3-5 minutes for 1 gram doses (acceptable alternative) 1
- Extended infusion: 3 hours when MIC ≥8 mg/L or treating CRE/CRAB 4, 2
Extended infusion over 3 hours is critical for optimizing pharmacodynamic targets when treating resistant organisms or when meropenem MIC is ≥8 mg/L for CRE or ≥32 mg/L for CRAB. 4
Dosing in Renal Impairment
Dose reduction is mandatory when creatinine clearance falls below 50 mL/min. 1
Renal Dosing Algorithm
| Creatinine Clearance | Dose | Interval |
|---|---|---|
| >50 mL/min | Standard dose (500 mg or 1 g) | Every 8 hours |
| 26-50 mL/min | Standard dose | Every 12 hours |
| 10-25 mL/min | Half the standard dose | Every 12 hours |
| <10 mL/min | Half the standard dose | Every 24 hours |
Important caveat: There is inadequate data for dosing in patients on hemodialysis or peritoneal dialysis—use extreme caution and consider infectious disease consultation. 1
Pediatric Dosing
Children ≥3 Months of Age with Normal Renal Function
Dose meropenem based on weight and infection type, with maximum doses capped at adult equivalents. 1
- cSSSI: 10 mg/kg every 8 hours (max 500 mg per dose) 1
- Complicated intra-abdominal infections: 20 mg/kg every 8 hours (max 1 gram per dose) 1
- Meningitis: 40 mg/kg every 8 hours (max 2 grams per dose) 1
- cSSSI caused by P. aeruginosa: 20 mg/kg every 8 hours (max 1 gram per dose) 1
For children >50 kg, use adult dosing. 1
Infants <3 Months of Age
Dosing depends on both gestational age (GA) and postnatal age (PNA), with all doses given as 30-minute infusions. 1
| Gestational & Postnatal Age | Dose | Interval |
|---|---|---|
| <32 weeks GA, PNA <2 weeks | 20 mg/kg | Every 12 hours |
| <32 weeks GA, PNA ≥2 weeks | 20 mg/kg | Every 8 hours |
| ≥32 weeks GA, PNA <2 weeks | 20 mg/kg | Every 8 hours |
| ≥32 weeks GA, PNA ≥2 weeks | 30 mg/kg | Every 8 hours |
Treatment Duration
For complicated intra-abdominal infections, treat for 5-7 days, individualized based on source control adequacy and clinical response. 2, 3
- Discontinue within 24 hours if cholecystitis is limited to the gallbladder wall and cholecystectomy is performed 2
- Duration should be guided by infection site, adequacy of source control, and clinical improvement 2, 3
Combination Therapy for Resistant Organisms
Carbapenem-Resistant Enterobacteriaceae (CRE)
Always use combination therapy—never meropenem monotherapy—when treating CRE infections. 2, 3
- Requires extended 3-hour infusion 4, 2
- Indicated when meropenem MIC ≤8 mg/L 4
- Combine with at least one other active agent 4
Carbapenem-Resistant Acinetobacter baumannii (CRAB)
Consider high-dose extended-infusion meropenem (2 grams every 8 hours over 3 hours) as part of combination therapy when meropenem MIC ≤8 mg/L for CRAB pneumonia or bloodstream infections. 4
- Polymyxin-meropenem combinations rank highest for clinical cure in CRAB pneumonia 4
- For CRAB with meropenem MIC ≥32 mg/L, combination therapy with extended infusion is recommended 4
- Colistin-carbapenem combinations showed 91.7% probability of improving clinical cure 4
Critical Clinical Considerations
Seizure Risk
High doses of meropenem (particularly >6 grams/day) are associated with increased seizure risk. 4
- Monitor closely in patients with CNS disorders or renal impairment 4
- Meropenem has lower seizure risk than imipenem 5, 6
No Loading Dose Required
Unlike colistin, tigecycline, or vancomycin, meropenem does not require a loading dose. 2
- Optimization is achieved through extended infusion, not loading doses 2
- Start with standard dosing immediately 2, 1
Spectrum Gaps
Meropenem is NOT effective against methicillin-resistant S. aureus (MRSA), vancomycin-resistant enterococci (VRE), or Stenotrophomonas maltophilia. 2, 5
- Active against methicillin-susceptible S. aureus only 2, 1
- Vancomycin-susceptible E. faecalis is covered, but not E. faecium 1, 7
Pharmacodynamic Target
Meropenem exhibits time-dependent bactericidal activity; the critical parameter is maintaining free-drug concentrations above the MIC for approximately 40% of the dosing interval (%T>MIC). 8
- Extended infusions optimize this target for resistant organisms 8
- Standard intermittent dosing is adequate for susceptible pathogens 8
Drug Compatibility Warning
Do not mix meropenem with other drugs in the same solution or infusion container. 1